6.58 Найдите сумму: a) 8/13 + 3/13; в) 18 + 4/19; д) 2 7/9 + 8/9; ж) 4 1/2 + 3 1/4; б) 31/60 + 29/60; г) 23 + 9/10; e) 15 8/11 + 4 3/11; з) 5 1/7 + 3 20/21.

Ответ:

a) 8/13 + 3/13 = 11/13

б) 31/60 + 29/60 = 60/60 = 1

в) 18 + 4/19 = 18 4/19

г) 23 + 9/10 = 23 9/10

д) 2 \(\frac{7}{9}\) + \(\frac{8}{9}\) = 2 + \(\frac{7+8}{9}\) = 2 + \(\frac{15}{9}\) = 2 + 1 \(\frac{6}{9}\) = 3 \(\frac{6}{9}\) = 3 \(\frac{2}{3}\)

е) 15 \(\frac{8}{11}\) + 4 \(\frac{3}{11}\) = 19 \(\frac{11}{11}\) = 20

ж) 4 \(\frac{1}{2}\) + 3 \(\frac{1}{4}\) = 4 \(\frac{2}{4}\) + 3 \(\frac{1}{4}\) = 7 \(\frac{3}{4}\)

з) 5 \(\frac{1}{7}\) + 3 \(\frac{20}{21}\) = 5 \(\frac{3}{21}\) + 3 \(\frac{20}{21}\) = 8 \(\frac{23}{21}\) = 9 \(\frac{2}{21}\)